Field of the Invention
The present invention relates to a flowability improver for improving flowability during a molding process without ruining inherent properties (transparency, impact resistance, high rigidity, mechanical strength, surface layer peeling resistance, heat resistance, chemical resistance, and the like) of a polycarbonate resin and a polyarylate resin, high-flowability polycarbonate resin composition and polyarylate resin composition that contain the flowability improver, and a molded article thereof.
Discussion of the Background
The polycarbonate resin and the polyarylate resin have excellent mechanical and thermal properties and thus are widely used industrially in fields of OA (office automation) equipment, information and communication equipment, electronic and electrical equipment, household appliances, automobile parts, building materials, and the like. However, these resins have high melt viscosity, and thus are poor in flowability and moldability.
In recent years, along with progresses in increase in size, decrease in thickness, complication in shape and sophistication of molded articles of these resin compositions and a growing interest in environmental problems, there has been a demand for a technology for improving the melt flowability and the moldability of these resin compositions without ruining excellent characteristics of molded articles formed from the polycarbonate resin and the polyarylate resin.
For example, as a method for improving melt flowability of an aromatic polycarbonate-based resin composition, a method in which a molecular weight of the aromatic polycarbonate-based resin itself is reduced is well known (Patent Document 1). However, for a polycarbonate resin of a low molecular weight, due to the low molecular weight, a temperature range of changing from ductile fracture to brittle fracture increases and thus there are problems such as that impact resistance strength is significantly reduced even at room temperature and that hydrolysis resistance also decreases.
Patent Document 2 describes that flowability is improved by adding a pentaerythritol-based ester compound and lowering the molecular weight of a polycarbonate resin by transesterification. This method allows the flowability to be improved without significantly ruining various characteristics. However, sufficient impact strength is not maintained, and there is also a concern about yellowing due to transesterification. Further, aliphatic esters of phthalic acid such as dioctyl phthalate and dibutyl phthalate commonly used in other resins as plasticizers, or phosphate esters such as tricresyl phosphate and diphenyl cresyl phosphate, and the like lack affinity with aromatic polycarbonate resins and cause mechanical and thermal properties to be remarkably degraded.
As a method for improving flowability without ruining these characteristics, Patent Document 3 describes that a specific bisphenol-based compound is added. However, in this method, since a low molecular weight compound is added, there is a concern that the additive may bleed out during molding.
Examples of a polymer flowability improver include a method of blending a copolymer obtained by polymerizing several kinds of (meth) acrylic acid ester monomers and aromatic alkenyl compounds in a polycarbonate resin (Patent Documents 4 and 5) and a method of blending a liquid crystalline resin (Patent Document 6). However, in these methods, although melt flowability during a molding process is improved, compatibility between the polycarbonate resin and the blends is poor and thus there is a problem that transparency of an obtained molded article cannot be maintained.
Patent Document 7 describes that transparency and mechanical strength are maintained by using a copolyester carbonate resin as a flowability improver of a polycarbonate-based resin. However, in order to improve the flowability, a blending amount of 20 parts by weight or more of the copolyester carbonate resin is necessary when the entire resin composition combining the polycarbonate-based resin and the copolyester carbonate resin is 100 parts by weight. Further improvement in functional expression efficiency is demanded.
Patent Document 8 describes that, by adding a liquid crystalline thermoplastic resin, in which mesogen groups and spacers are alternately polycondensed, to another general-purpose resin, thermal conductivity of the general-purpose resin can be improved. However, in Patent Document 8, there is no description regarding whether or not flowability during a molding process can be improved without ruining transparency and mechanical properties of a polycarbonate resin or a polyarylate resin when the liquid crystalline thermoplastic resin is added to the resins.
Patent Document 9 describes liquid crystalline resin particles formed from biphenol or bisphenol A and an aliphatic dicarboxylic acid as a component of a toner composition, and describes that the liquid crystalline resin having a melt viscosity is suitable for the toner composition. However, in Patent Document 9, there is no description regarding whether or not the liquid crystalline resin can improve flowability during a molding process without ruining transparency and mechanical properties of a polycarbonate resin or a polyarylate resin.
Patent Document 1: Japanese Patent Laid-Open Publication No. Sho 62-297319 (published on Dec. 24, 1987).
Patent Document 2: International Publication No. 2012/068075 (published on May 24, 2012).
Patent Document 3: Japanese Patent Laid-Open Publication No. Hei 1-271456 (published on Oct. 30, 1989).
Patent Document 4: Japanese Patent Laid-Open Publication No. 2013-213153 (published on Oct. 17, 2013).
Patent Document 5: Japanese Patent Laid-Open Publication No. 2011-26593 (published on Feb. 10, 2011).
Patent Document 6: Japanese Patent Laid-Open Publication No. 2002-249656 (published on Sep. 6, 2002).
Patent Document 7: Japanese Patent Laid-Open Publication No. Hei 4-275360 (published on Sep. 30, 1992).
Patent Document 8: International Publication No. 2011/033815 (published on Mar. 24, 2011).
Patent Document 9: Japanese Patent Laid-Open Publication No. Sho 61-69861 (published on Apr. 10, 1986).